style: uniform grids, profile border, remove NOUVEAU badge

- Toutes les pages utilisent grid-cols-1 sm:2 lg:3 xl:4 gap-8
- Cadre gradient visible en permanence sur l'avatar profil
- Suppression du badge NOUVEAU sur les épisodes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/components/EpisodeCard.tsx

@@ -69,12 +69,6 @@ export default function EpisodeCard({ episode, onPlay, onDetails }: EpisodeCardP
               LU
             </div>
           )}
-          {isNew && (
-            <div className="px-2.5 py-1 rounded-lg bg-[var(--accent-gold)]/90 backdrop-blur-md border border-white/20 text-[9px] font-black text-white uppercase tracking-widest flex items-center gap-1 shadow-lg animate-pulse">
-              <Sparkles className="w-3 h-3" />
-              NOUVEAU
-            </div>
-          )}
         </div>
 
         {/* Hover Play Button Overlay */}

frontend/src/components/Header.tsx

@@ -43,7 +43,7 @@ export default function Header({ title, subtitle, user, onLogout }: HeaderProps)
                   <span className="text-[10px] font-medium text-[var(--text-secondary)] uppercase tracking-widest">Premium Member</span>
                </div>
                <div className="relative group/profile">
-                  <div className="w-12 h-12 rounded-2xl p-[1px] bg-gradient-to-tr from-[var(--accent-primary)]/50 to-[var(--accent-secondary)]/50 group-hover/profile:from-[var(--accent-primary)] group-hover/profile:to-[var(--accent-secondary)] transition-all">
+                  <div className="w-12 h-12 rounded-2xl p-[1px] bg-gradient-to-tr from-[var(--accent-primary)] to-[var(--accent-secondary)] transition-all">
                     <div className="w-full h-full rounded-2xl bg-[var(--bg-primary)] flex items-center justify-center overflow-hidden">
                       {user.avatar ? (
                         <img src={user.avatar} alt={user.username} className="w-full h-full object-cover" />